Many hybrid electric applications operate more effectively with a two-speed transmission. This capability is certainly beneficial to hybrid electric applications such as transit buses and military vehicles, which require a wide range of operational speeds. In these applications, electric motors are used to provide driving input to a drive axle or gear box that ultimately drives the vehicle.
In the example of a transit bus, an electric motor can power a drive axle extending between a pair of vehicle wheels. The drive axle typically includes a carrier that houses a differential gear assembly, which allows speed differentiation between laterally opposed wheels as the bus negotiates a turning maneuver.
In the example of a military vehicle, such as a tracked vehicle for example, the electric motor can power a gear box, or a series of gear boxes, to power a final drive associated with laterally spaced tracks located at sides of the tracked vehicle. The electric motor could also be used in combination with the gear boxes to steer the tracked vehicle. Traditionally, a series of electric motors are required to accomplish both driving and steering functions.
Typically, the electric motors are coupled to drive existing gear box and drive axle configurations. To achieve lower speed outputs from high speed motors, additional gear boxes or transmissions may also be required. Additional gear boxes are not desirable because the gear boxes occupy valuable packaging space that is needed for other vehicle components.
For the above reasons, it would be desirable provide a more compact electric motor drive that incorporates two-speed capability, with driving output, without requiring a proliferation of gear boxes. The electric motor drive should be robust and easy to assemble in addition to overcoming other deficiencies in the prior art as outlined above.